Swap should be better done native?

[Martin Buchholz]

On Tue, Mar 30, 2010 at 07:39, Ulf Zibis <Ulf.Zibis at gmx.de> wrote:
> In java.nio.Bits, there are several swap methods.

> Shouldn't this be done better by a native method, as popular CPU's IMO would
> do that faster, and HotSpot easily could inline the single instruction?

http://cr.openjdk.java.net/~martin/webrevs/openjdk7/nioBits.java/

Please study ByteArrayAccess.java and SwapMicroBenchmark.java

Can you measure a performance improvement from my change?

> Additionally, in current XByteBuffer implementations the term (x << 0) is
> frequently used.
> Martin Buchholz has reported, that those zero-shifts reside in the byte
> code, so IMO should be refactored, as at least interpreter would be
> throttled by that.

Probably hotspot can optimize it away, but why not help?

Martin